High frequency wave modulation



Dec. 4, 1934. M. VON ARDENNE 1,932,771 HIGB FREQUENCY WAVE MODULATION 7 Filed Nov. 25, 1951 a, 1 I I 9 1 A 5 x I 25 I J2 a, 1C 1: J;

Jkzyezz'for:

Patented Dec. 4, 1934 UNITED STATES HIGH FREQUENCY WAVE MODULATION Manfred von Ardenne, Berlin, Germany, assignor to Radioaktiengesellschaft D. S. Lowe, Berlin- Steglitz, Germany, a company of Germany Application November 23, 1931, Serial No. 576,850 In Germany November 22, 1930 Claims.

In the erection of a multiple radio system employing ultra-short waves, which are modulated with a plurality of high frequencies, certain difficulties are encountered insofar as it is a ques- 5 tion of covering territories which are larger than the range, i. e., the optical range of the ultrashort waves. If, for example, a town of the size of Berlin is to be furnished with amultiple radio I or television program, it is nevertheless to be expected, even if employing 9 metre waves and erecting the sender at an extremely elevated point, that perfect reception will not be possible in all suburbs.

Under these circumstances it is suggestive to suitably distribute 2 or 3 ultra-short wave senders over the area of the town in order to satisfy all subscribers. With an arrangement of this kind, however, there will be, more particularly in the central part of the town, large areas where 20.:the ultra-short waves arrive with approximately the same strengths of field. In order in these areas to separate the ultra-short waves a more or less considerable selection will be required dependent on the spacing of the waves.

The present invention dealswith the question of utilizing the selective properties of normal radio receivers for separating a plurality of ultra-short wave senders, and thus avoiding the necessity of providing particularly effective selecting means in the requisite ultra-short wave auxiliary apparatus.

Fundamentally, these difficulties may be avoided by modulating different high frequencies on to the different ultra-short wave transmitters,

(all of which frequencies, however, are preferably included within the range of one octave. If the ultra-short wave senders were each modulated with 3 high frequencies, each high frequency is modulated by a program, (it may also be the .Isame three programs), the different high frequencies, according to the additional subject matter of the invention, are intended to be distributed in such fashion over the available interval, for example 300-600 m., that even in the ."case when the different ultra-short wave senders are demodulated simultaneously by a simple, non-selective auxiliary apparatus, there are no disturbances, or merely a minimum thereof. This is the case if the high frequencies are dis .tributed evenly over the wave range.

In this connection it is to be observed that the octave requires to be precluded, i. e., that the waves A to be selected require to comply with the condition A1A 2A1, whereby A1 represents the lower wave length limit.

Disturbances may also occur in connection with multiple broadcasting of this nature over the plurality of ultra-short wave transmitters when the deviations of the ultra-waves reach such a level that the resultant difference frequencies fall within the high frequency range employed, for example 300-600 in. I

If, for example, it is desired to transmit three programs, and three ultra-short wave senders are to be employed for influencing the receivers, there are preferably selected for the three programs more particularly nine different wave lengths, which are preferably disposed within the selected octave with equal but greatest possible frequency spacing. If then the waves A1, A2, A3, A4 etc. are in the order of the range of their wave lengths, the ultra-short wave transmitters S1, S2, S2 will preferably be so modulated that one ultra-short wave transmitter is modulated by the waves A1, A4, A7, the second by A2, A5, A8, and the third by the waves A3, A6, A9. The threepr'ograms are then preferably distributed in such fashion over the single waves that the one program is carried by the waves A1, A2 and As, the second by the waves A4, A5 and A6, and the third by the waves A7, A8 and A9.

As already stated above, the invention may be employed not only in respect of speech or tone modulated high frequencies, but also for high frequency bands, such as are frequently used, for example, in connection with television. The high frequency bands are then preferably transferred in unitary fashion either to the higher or to the lower parts of the high frequency range to be transmitted.

The invention is illustrateddiagrammatically in Figs. 1 and 2.

In Fig. 1 the high frequency generators the waves of which are to be transmitted are designated A1, A2, A3, A4, A5,'As, A7, A3, A9, viz, in the order of their wave lengths. S1, S2, S3 are three ultra-short wave. transmitters, which are controlled by the high frequency generators A1, A4 and A7, A2, A5 and A8, and A2, A6 and A9 respectively.

Fig. 2 shows a possible form of embodiment of a transmission system of this nature. It is assumed, for example, that the oscillatory circuits l and 2 of the transmission tubes oscillate in the frequencies A2, A5 and As. The three generators. are modulated according to one of the known modulation systems, for example according to the principle of the parallel tube control. The parallel tubes 4 are controlled by a microphone 6 or similar elements through the medium of a repeater 5, and thus modulate the high frequency generator. The three high frequency generators x2, A5 and Ms control through the medium of coupling coils '7 a modulating valve 8, which is situated in the grid circuit of the short-wave transmitter tube 9. In the anode circuit of this tube, which is connected for self-excitation, there is an oscillatory circuit 10, which passes the modulated ultra-short wave energy to the radiating system (aerial ll). ing batteries, 13 the anode batteries, 14 the initial grid voltage batteries and 15 the microphone batteries. 16 are the high frequency, and 1'7 the low frequency chokes.

As already mentioned above, it is naturally also possible to employ both other forms of ultrashort Wave transmission systems as well as other high frequency generator systems, and also in the case of both systems to provide other forms. of modulation. The transmission of the modulated high frequency oscillation to the ultra-short wave transmitter may also be performed in various different manners, dependent on the fact asto whether the high frequency generators are situated at or away from the transmitter. In the case of distant transmission it is of course necessary to conduct the high frequency energy of the oscillatory circuit 2 to an aerial system, to receive the radiated energy, and to amplify the same or pass it to the coil 7.

I claim: V

1. In an arrangement for transmitting one or more programs, two or more'ultra-short wave transmitters, means for generating several groups of intermediate frequencies, means for modulating each of said groups by the same program, each of said ultra-short wave transmitters being modulated by one intermediate frequency of each of said several groups of intermediate frequencies. i

2. In an arrangement for transmitting one or more programs, two or more ultra-short wave transmitters, means for generating several groups of intermediate frequencies, means for modulating each of said groups by the same program, each of said ultra-short wave transmitters being modulated by one intermediate frequency of each of said several groups of intermediate fre- 12 are the various heatquencies, the frequencies of said ultra-short wave transmitters differing from each other to such extent, that the difference frequencies are situated outside the range of the modulating high frequency bands.

3. In an arrangement for transmitting one or more programs; two or more ultra-short wave transmitters, means for generating several groups of intermediate frequencies, means for modulating each of said groups by the same program, each of said ultra-short wave transmitters being modulated by one intermediate frequency of each of said several groups of intermediate frequencies, said groups of intermediate frequencies, limited to and distributed over the range of a single octave, whereby the wave, corresponding with the octave, remains unemployed.

4. In an arrangement for transmitting one or more programs, two or more ultra-short wave transmitters, means for generating several groups of intermediate frequencies, means for modulating each of said groups by the same program, each of said ultra-short wave transmitters being modulated by one intermediate frequency of each of said several groups of intermediate frequencies, said intermediate frequencies distributed to said groups in such a manner that the intermediate frequencies in each group, for transmitting the same program, difiering from each other to the greatest possible extent.

5. In an arrangement for transmitting one or more programs, two or more ultra-short wave transmitters, means for generating several groups of intermediate frequencies, means for modulating each of said groups by the same pro-- gram, the intermediate frequencies modulated by the same program being the nearest to each other, each of said ultra-short wave transmitters being modulated by one intermediate frequency of each of said several. groups of intermediate frequencies, said intermediate frequencies distributed to said groups in such a manner that the intermediate frequencies in each group, for transmitting the same program, differing from each other to the greatest possible extent.

MANFRED VON ARDENNE. I 

